From: Paul Cercueil <paul@crapouillou.net>
To: Christophe Leroy <christophe.leroy@c-s.fr>
Cc: Guenter Roeck <linux@roeck-us.net>,
Wim Van Sebroeck <wim@linux-watchdog.org>,
od@zcrc.me, linux-watchdog@vger.kernel.org,
linux-kernel@vger.kernel.org
Subject: Re: [PATCH v2 4/4] watchdog: jz4740: Make probe function __init_or_module
Date: Sat, 08 Jun 2019 11:57:01 +0200 [thread overview]
Message-ID: <1559987821.1815.0@crapouillou.net> (raw)
In-Reply-To: <0dc0fd0a-54fc-5d70-af78-1874b5ece418@c-s.fr>
Hi Christophe,
Le sam. 8 juin 2019 à 9:51, Christophe Leroy <christophe.leroy@c-s.fr>
a écrit :
> Hi Paul,
>
> Le 07/06/2019 à 18:24, Paul Cercueil a écrit :
>> This allows the probe function to be dropped after the kernel
>> finished
>> its initialization, in the case where the driver was not compiled as
>> a
>> module.
>
> I'm not sure that's what __init_or_module flag does.
>
> As far as I understand, this flag makes the function being dropped
> only when the kernel is built without modules support, ie without
> CONFIG_MODULES. See
> https://elixir.bootlin.com/linux/latest/source/include/linux/module.h#L145
So it doesn't depend on the driver being built-in or compiled as a
module?
> In addition, I'm not sure you can simply define a probe function as
> __init. What if someone tries to unbind and rebind the device through
> sysfs for instance ?
Ouch. I feel stupid now.
> It seems there is a special function called __platform_driver_probe()
> for registering devices when the probe function is to be in __init,
> see
> https://elixir.bootlin.com/linux/latest/source/drivers/base/platform.c#L684
Yes, but only usable by drivers that won't defer probe, and it removes
the bind/unbind attributes from sysfs,
so it shouldn't be used for non-critical drivers, I think.
> Christophe
>
>>
>> Signed-off-by: Paul Cercueil <paul@crapouillou.net>
>> ---
>>
>> Notes:
>> v2: New patch
>>
>> drivers/watchdog/jz4740_wdt.c | 2 +-
>> 1 file changed, 1 insertion(+), 1 deletion(-)
>>
>> diff --git a/drivers/watchdog/jz4740_wdt.c
>> b/drivers/watchdog/jz4740_wdt.c
>> index 7519d80c5d05..2061788c1939 100644
>> --- a/drivers/watchdog/jz4740_wdt.c
>> +++ b/drivers/watchdog/jz4740_wdt.c
>> @@ -157,7 +157,7 @@ static const struct of_device_id
>> jz4740_wdt_of_matches[] = {
>> MODULE_DEVICE_TABLE(of, jz4740_wdt_of_matches);
>> #endif
>> \x7f-static int jz4740_wdt_probe(struct platform_device *pdev)
>> +static int __init_or_module jz4740_wdt_probe(struct platform_device
>> *pdev)
>> {
>> struct device *dev = &pdev->dev;
>> struct jz4740_wdt_drvdata *drvdata;
>>
next prev parent reply other threads:[~2019-06-08 9:57 UTC|newest]
Thread overview: 10+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-06-07 16:24 [PATCH v2 0/4] JZ4740 watchdog cleanups Paul Cercueil
2019-06-07 16:24 ` [PATCH v2 1/4] watchdog: jz4740: Use register names from <linux/mfd/ingenic-tcu.h> Paul Cercueil
2019-06-07 16:24 ` [PATCH v2 2/4] watchdog: jz4740: Avoid starting watchdog in set_timeout Paul Cercueil
2019-06-07 16:24 ` [PATCH v2 3/4] watchdog: jz4740: Drop dependency on MACH_JZ47xx Paul Cercueil
2019-06-07 16:24 ` [PATCH v2 4/4] watchdog: jz4740: Make probe function __init_or_module Paul Cercueil
2019-06-07 17:29 ` Guenter Roeck
2019-06-08 7:51 ` Christophe Leroy
2019-06-08 9:57 ` Paul Cercueil [this message]
2019-06-11 5:16 ` Christophe Leroy
2019-06-11 11:02 ` Guenter Roeck
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